Questions tagged [rf]
Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.
0
votes
0answers
17 views
Schematic diagram of a double-balanced Gilbert cell mixer
For the following gilbert cell circuit, I have few questions.
I understand that R1 to R4 as well as M1 to M6 are parts of the double-balanced differential topology which helps to eliminate the DC ...
1
vote
1answer
48 views
Is it parallel or series
In the figure below, an RLC circuit, the author in the book says, that the resonant circuit sees Rs and RL to be parallel so he combined them (R total = the parallel sum of Rs and RL), is it right ...
0
votes
1answer
51 views
“RF energy harvesting” Can rf transmitter be a rf signal generator?
I'm trying to build an rf energy harvester. But having some problem.
The harvester should collect the 915Mhz signal.
Can I use 915Mhz rf transceiver + 915mhz amplifier as the rf signal source?
How ...
1
vote
3answers
141 views
How to find the frequency of any device?
Are there devices which can figure out at what frequency every device transmitting radio frequencies operate at precisely? Say from a high of 2.4 GHz microwave to a low of 402 Hz pacemaker.
0
votes
0answers
11 views
Single Ended DAC to Differential Input Modulator
I'm trying to drive a differential input IQ modulator (LT5571) with a single ended DAC (MCP4912) for modulation of a narrow band signal (~10kHz max).
Because of the nature of the low frequency ...
0
votes
0answers
49 views
What transmissions technology has the largest range, with the lowest power consumption? [on hold]
Perhaps this isn't the right question (or right place to ask it) but I am building a fixed wing "drone" and I would love at least 1 way communication (from the drone to a station) for the majority of ...
6
votes
4answers
2k views
Can I run 125kHz RF circuit on a breadboard?
I was wondering if making a low frequency RF circuit on a breadboard is viable.
-1
votes
0answers
32 views
Pair 433 MHz RF devices [on hold]
I need to build system "turn on lamp with wireless PIR sensor". I'm planning to buy 433 MHz PIR sensor and somehow pair it with 433 MHz relay. But how to pair them? How to get codes from transmitter ...
0
votes
1answer
31 views
Cutoff or Corner Frequency for Coax Cable
I'm trying to understand better what the significance of the cutoff frequency for coax cables is. I have a case where a cable is considered for use at frequencies up to 3% higher than the manufacturer'...
0
votes
0answers
24 views
RF device connection issue
I have a surface acoustic wave based separator device built on piezoelectric (PZT) substrate and this is mounted on a PCB for the external connection as you can see from the picture.
When I was ...
1
vote
2answers
73 views
Smith chart of λ/4 Transmission Line
I came across the following slide on power combiner circuit and I have questions about it.
Why traverse across the upper half circle ?
Why "ZT-line is the geometric mean of Zout and Zin." ?
2
votes
0answers
48 views
Audio PWM over Radio [on hold]
I'm working on a project in which I must send audio over RF such that remote speakers can pick up the signal around a house/apartment. The goal is to broadcast music from a single device somewhere in ...
0
votes
0answers
17 views
EN 300 328 Receiver (RX) Blocking | BLE DTM Implementation with Signaling Analyzers?
We are working through a Nordic NRF 52832 certification, and are getting the device CE tested.
We are running into some issues getting our device connected to the R&S CMW 500 signaling analyzer ...
1
vote
0answers
91 views
First PCB project design critique requested (RF) EDITED
This is my first ever RF PCB project and it'd be great to receive some guidance to make this project 'first-time-right'.
It's purpose is to transmit and receive signals at two different frequencies: ...
0
votes
1answer
56 views
In actual OFDM trasmitter, is the stepwise waveform after IFFT put on the carrier as it is?
I simulated OFDM on MATLAB,though,the spectrum of it is not white(flat shape).
Why?
IFFT circuit of actual transmitter uses higher IFFT order than the count of subcarriers?
P.S.
I simulated with the ...
1
vote
0answers
20 views
Realizing a prototype filter in ADS or any other simulator
I'm trying to design a stub-filter, and I'm stuck on realizing the filter design using Richard's transformations and Kuroda identities.
I'm building a 5th order Chebyshev LP-filter for 2.6 GHz pass-...
-1
votes
0answers
50 views
Is there any 433mhz rf transmiter/module/transceiver can work at 1v voltage or lower? [closed]
I am finding this kind of transmitter but it seems there is no such kind of components. Does anybody know? Thanks
Because I want to use a msp430l092 which work can at 0.9v at least. Combining it ...
2
votes
1answer
43 views
What should be assumed regarding the upper frequency of sma connectors
There are infinitely many sellers of sma connectors of various kind in ebay or other stores. This one is an example.
But they very seldom specify what is the maximum frequency at which the device can ...
3
votes
0answers
41 views
Microphonic SAW transmitter?
I built this very simple SAW transmitter, with a simple "spring" antenna for the right frequency. To test it, I tuned a portable receiver to around 433.92Mhz and fine tuned it until I heard silence. ...
0
votes
0answers
25 views
Need guidelines with creating chip module footprint [closed]
I am trying to design my own RF PCB using online pcb-editor Easyeda. My circuit uses RF module cc1101. I couldn't find matching PCB library for my module so I decided to create one myself. I basically ...
0
votes
0answers
31 views
Reactance of a dipole antenna
I am interested in calculating the input impedance \$Z_{in}=R_{in}+jX_{in}\$ of a dipole antenna numerically. However, I am unsure how I would compute the imaginary part of the impedance (\$X_{in}\$).
...
0
votes
1answer
17 views
Conversion Gain Definition for DSB-SC Upconversion
If I multiply a baseband signal \$A cos(C\omega t)\$ and a carrier signal \$B cos(D\omega t)\$, the result is \$\frac{AB}{2} [cos(C-D)\omega t+cos(C+D)\omega t]\$, which is a double sideband, ...
0
votes
1answer
32 views
I cannot find information about some chips in 3 stage LNA circuit
Hi, here you can see 3-stage LNA circuit. I want to know information about two chips(6 pins) with R8 mark at the top. Also, 4 chips with D4 mark with 3 pins at right side. Is there anyone who has a ...
0
votes
0answers
39 views
What kind of Modulation? Who transmits on 850 MHz (LTE-Uplink or GPRS?)?
Hey, I found an interesting Signal on 850MHz (in Germany). It is not symmetric and very strong (relative to many others due to bad antennas). On the right side the bandwith is permanently used, on the ...
0
votes
0answers
28 views
Cheap RF 433.92MHz design, PCB track antenna [duplicate]
I'm doing a RF remote control project using a PCB with microcontroller and with simple onboard antenna layout as transmitter and a 433.92MHz receiver RWS-371F-6 model. Here is the datasheet of the ...
2
votes
2answers
112 views
160MHz Ambient Office Noise?
I've got a shielded tent in our office and I see one ambient element I don't have a good explanation for.
We see some ambient noise at 700MHz - 800MHz which I guess is cell-band noise.
But there is ...
1
vote
0answers
103 views
On purpose shorted capacitor in schematic
I've come across this schematic from an RF device where I've spotted some weird configuration of capacitors. There are, all around the schematic, some shorted capacitors which I can't figure out what ...
0
votes
1answer
53 views
RF Design / Calculations - 433.92MHz, PCB antenna, values of capacitors
I'm doing a RF remote control project using a PCB with microcontroller and with simple onboard antenna layout as transmitter and a 433.92MHz receiver RWS-371F-6 model. Here is the datasheet of the ...
6
votes
2answers
116 views
Tube transmitter tuning
I am trying to tune/tweak/repair this transmitter for a friend of mine. It is oscillating, and it has rf power on the antenna, but it just doesn't seem as "strong" as it should be.
The diagram says ...
0
votes
3answers
51 views
Minimizing reflection coefficient of a low-pass filter
I'm trying to figure out (with not a lot of success) as to what I need to consider when I want to minimize reflection coefficient below a certain point. I'm trying to design a low-pass shunt stub ...
0
votes
1answer
29 views
S21 VNA Connector & Cable Loss?
I've tuned plenty of RF devices using my VNA for impedance matching. But I've never done an S21 measurement.
I have a shielded tent with some connectors and SMA cables that are going to introduce ...
0
votes
1answer
44 views
Tube transmitter plate current meter question
Can I install the mA meter in this schematic directly in the circuit?
This is the high voltage plate supply and there is RF on it.
The diagram doesn't specify if there is any circuitry to adapt the ...
1
vote
2answers
70 views
RF Antenna Matching circuit and PCB design for 868 MHz SigFox device
I'm designing a Sigfox sensor device based on WISOL/SFM10R1 a SigFox verfied module by WiSOL and Atmega328.
I need to understand the parameters for 868 MHz RF Antenna Matching circuit and PCB trace ...
0
votes
1answer
65 views
How can I design a high speed RF peak detector?
The diode-capacitor solution would not work in my application because the operating frequency of my circuit is about 1.4GHz. So what is an alternative solution that would work in such high frequencies?...
0
votes
1answer
32 views
Phased array receiver circular polarization
In a phased array system, what will have to change in a receiver's architecture if it needs to work for both linear and circular polarization?
I saw in one article it is said "Supports automatic ...
0
votes
2answers
78 views
How same frequency signal with different power are produced?
My router have settings to configure transmission power and as i know energy of a signal is given by
$$
E = h\nu
$$
where
\$E\$ is the energy of the signal,
\$h\$ is Planck's constant,
\$\nu\$ is ...
0
votes
1answer
57 views
(Antenna impedance matching) How to find the load impedance
I'm working on a project that requires impedance matching and I'm going to match a 50 Ω antenna to a RF amplifier SST12LP22. However, I'm not sure how can I get the impedance of the amplifier from the ...
2
votes
1answer
86 views
In this Foster Seeley discriminator, what is the purpose of capacitor C3?
I understand the whole circuit, except for the use of capacitor 3. What's its purpose in here?
0
votes
0answers
63 views
How does this transmitter work/how to tune it?
I have used a few 433MHz ASK transmitters. They're cheap, readily available, and work reasonably well.
Based on this application note from Murata I tried to build my own.
I replaced the NE68030 ...
0
votes
2answers
56 views
How does this simple FM slope detector work?
I understand what happens from the diode onwards, it's a rectifying amp and a low pass filter that filters any unwanted frequencies from the carrier, but what is going on in terms of voltage between ...
2
votes
1answer
115 views
How to measure radio signal strength
I am building several types of radio antennas, and I would like to test which is the most effective. I am wondering: What is the best way to measure the strength of the received signal?
It is at ~...
0
votes
1answer
53 views
designing Low-Pass Transmission Line Stub Filter
I'm trying to design a Low-Pass transmission line stub filter, and I have a few question regarding it.
I'm rather new to RF-circuit design, so please bear with me.
If my desired specs include the ...
0
votes
1answer
23 views
Absorber effect on EM RF pattern
If I have an omnidirectional antenna and put a perfect reflector plane near it (in the near field), it will obviously change its radiation pattern in the direction opposite the reflector. ...
2
votes
1answer
166 views
Sub 1 GHz communication - long range at 500kbps. Is my range estimate roughly correct?
When researching long range medium bitrate RF comms I came across the TI range. The TI CC1201 transceiver claims -97dBm sensitivity at 500-1000kbps. If the system is on the 868MHz band which is ...
0
votes
1answer
28 views
How to link 3 RF transceivers to 1 antenna
I'm not an RF designer, so excuse the newbie question:
How would I link three transceivers, say WiFi and two separate bluetooth transceivers, to a single antenna.
I have found a 3-way combiner ...
1
vote
0answers
25 views
What causes the fail-safe bit to be set in the SBUS protocol?
What causes the fail-safe bit to be set in the SBUS protocol?
I know that the when the link between the transmitter and receiver is lost, the fail-safe bit is set, however, what constitutes a 'lost ...
0
votes
1answer
41 views
Bitstream autocorrelation? - comparing two bitstreams - BER?
I am sending a PN9 sequence from a sender to a receiver and want to compare the received bitstream (RB) to the sent one (SB). I am assuming that the transmission will get distorted and want to somehow ...
2
votes
1answer
81 views
What is the fastest SiC MOSFET?
I would like to know what is the fastest SiC FET greater than or equal to 10A in a TO-247-3 package.
Currently I am using a C2M0280120D. My switching speed is 7 MHz. I want to know if there is a ...
1
vote
3answers
196 views
Homemade Faraday Cage?
I'm working in an office with a Wi-Fi router, desktop, and a few cell phones making RF noise.
I have an 8 feet long by a 3-feet wide table, and I have an Aaronia BICOLOG 30100 + spectrum analyzer + ...
1
vote
1answer
55 views
Drivers for high power RF switches
I am currently working on an RF project and using a high power RF SPDT switch. The control voltages of this switch are between 0V/-40V. If the control voltage is 0V, then the corresponding path is ON ...
